package com.zj.jdbc3Batis.tools;

import com.zj.util.JdbcPropertyLoader;

import javax.sql.DataSource;
import java.io.PrintWriter;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.*;
import java.util.LinkedList;
import java.util.logging.Logger;

public class JdbcPoolUtil {

    private static String url = JdbcPropertyLoader.getProperty("jdbc.url");
    private static String username = JdbcPropertyLoader.getProperty("jdbc.username");
    private static String password = JdbcPropertyLoader.getProperty("jdbc.password");
    int jdbcPoolInitSize =Integer.parseInt(JdbcPropertyLoader.getProperty("jdbc.poolInitSize"));
    /**
     * @ClassName: JdbcPool
     * @Description:编写数据库连接池
     * @author: 孤傲苍狼
     * @date: 2014-9-30 下午11:07:23
     *
     */
    public static class JdbcPool implements DataSource {
        private static String url = JdbcPropertyLoader.getProperty("jdbc.url");
        private static String username = JdbcPropertyLoader.getProperty("jdbc.username");
        private static String password = JdbcPropertyLoader.getProperty("jdbc.password");
        private static int jdbcPoolInitSize=Integer.parseInt(JdbcPropertyLoader.getProperty("jdbc.poolInitSize"));
        /**
         * @Field: listConnections
         *         使用LinkedList集合来存放数据库链接，
         *        由于要频繁读写List集合，所以这里使用LinkedList存储数据库连接比较合适
         */
        private static LinkedList<Connection> listConnections = new LinkedList<Connection>();

        static{
            try {
                for (int i = 0; i < jdbcPoolInitSize; i++) {
                    Connection conn = DriverManager.getConnection(url, username, password);
//                    System.out.println("获取到了链接" + conn);
                    //将获取到的数据库连接加入到listConnections集合中，listConnections集合此时就是一个存放了数据库连接的连接池
                    listConnections.add(conn);
                }
//                System.out.println(listConnections.get(0)==listConnections.get(2));

            } catch (Exception e) {
                throw new ExceptionInInitializerError(e);
            }
        }

        @Override
        public PrintWriter getLogWriter() throws SQLException {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public void setLogWriter(PrintWriter out) throws SQLException {
            // TODO Auto-generated method stub

        }

        @Override
        public void setLoginTimeout(int seconds) throws SQLException {
            // TODO Auto-generated method stub

        }

        @Override
        public int getLoginTimeout() throws SQLException {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public Logger getParentLogger() throws SQLFeatureNotSupportedException {
            return null;
        }

        @Override
        public <T> T unwrap(Class<T> iface) throws SQLException {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public boolean isWrapperFor(Class<?> iface) throws SQLException {
            // TODO Auto-generated method stub
            return false;
        }

        /* 获取数据库连接
         * @see javax.sql.DataSource#getConnection()
         */
        @Override
        public Connection getConnection() throws SQLException {
            //如果数据库连接池中的连接对象的个数大于0
            if (listConnections.size()>0) {
                //从listConnections集合中获取一个数据库连接
                final Connection conn = listConnections.removeFirst();
                System.out.println("listConnections数据库连接池大小是" + listConnections.size());
                //返回Connection对象的代理对象
                return (Connection) Proxy.newProxyInstance(JdbcPool.class.getClassLoader(), conn.getClass().getInterfaces(), new InvocationHandler(){
                    @Override
                    public Object invoke(Object proxy, Method method, Object[] args)
                            throws Throwable {
                        if(!method.getName().equals("close")){
                            return method.invoke(conn, args);
                        }else{
                            //如果调用的是Connection对象的close方法，就把conn还给数据库连接池
                            listConnections.add(conn);
                            System.out.println(conn + "被还给listConnections数据库连接池了！！");
                            System.out.println("listConnections数据库连接池大小为" + listConnections.size());
                            return null;
                        }
                    }
                });
            }else {
                throw new RuntimeException("对不起，数据库忙");
            }
        }

        @Override
        public Connection getConnection(String username, String password)
                throws SQLException {
            return null;
        }
    }
    /**
     * ====================================================================================
     * @Field: pool
     *          数据库连接池
     */
    private static JdbcPool pool = new JdbcPool();
    public static DataSource getPool(){
        return pool;
    }
    /**
     * @Method: getConnection
     * @Description: 从数据库连接池中获取数据库连接对象
     * @Anthor:孤傲苍狼
     * @return Connection数据库连接对象
     * @throws SQLException
     */
    public static Connection getConnection() throws SQLException{
        return pool.getConnection();
    }

    /**
     * @Method: release
     * @Description: 释放资源，
     * 释放的资源包括Connection数据库连接对象，负责执行SQL命令的Statement对象，存储查询结果的ResultSet对象
     * @Anthor:孤傲苍狼
     *
     * @param conn
     * @param st
     * @param rs
     */
    public static void release(Connection conn,Statement st,ResultSet rs){
        if(rs!=null){
            try{
                //关闭存储查询结果的ResultSet对象
                rs.close();
            }catch (Exception e) {
                e.printStackTrace();
            }
            rs = null;
        }
        if(st!=null){
            try{
                //关闭负责执行SQL命令的Statement对象
                st.close();
            }catch (Exception e) {
                e.printStackTrace();
            }
        }

        if(conn!=null){
            try{
                //关闭Connection数据库连接对象
                conn.close();
            }catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}
